This is a very hard question. I am working in Austria and I have to admit that I was never in such a situation. Never the less, I would put it that way. I would do what ever would be best for my safety. That means, if there is a threat to my safety i call dispatch to get the cops. I think with a murderer that would be the case. If the patient is running away... I am not going to hold them back or chase them. Thats not my job and it is to dangerous for me. Another question is: What are you doing when your patient does not want to go to hospital? In Austria he choose if the patient is fully aware of what he/she is doing. If we think that this is not the case, we call the cops, they call the public health officer and he decides weather the patient goes to hospital or not.